Method for transmitting and receiving signals using multi-band radio frequencies

ABSTRACT

A method for transmitting, by a base station, signals in a communication system. Control information for a subsidiary carrier band is transmitted to a mobile station via a primary carrier band. Data is transmitted to the mobile station via the subsidiary carrier band based on the control information and via the primary carrier band. Furthermore, the primary carrier band is a carrier frequency band which the mobile station initially attempts to access or via which information of a carrier aggregation configuration is transmitted. Additionally, the control information includes a logical index assigned to the subsidiary carrier band for the mobile station and a physical index of a frequency allocation band used as the subsidiary carrier band. The physical index corresponds to one of plural absolute frequency band indexes assigned to frequency allocation bands available in the communication system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of co-pending U.S. patent applicationSer. No. 12/849,635 filed Aug. 3, 2010, which is a continuation ofapplication Ser. No. 12/343,295 filed on Dec. 23, 2008 (now U.S. Pat.No. 8,340,014, issued on Dec. 25, 2012) which claims the benefit of U.S.Provisional Application No. 61/016,799 filed on Dec. 26, 2007, andKorean Patent Application Nos. 10-2008-0025817 filed on Mar. 20, 2008,10-2008-0075554 filed on Aug. 1, 2008, 10-2008-0084731 filed on Aug. 28,2008 and 10-2008-0096055 filed on Sep. 30, 2008. The entire contents ofall of the above applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for transmitting and receivingsignals, wherein multi-band IDs are specified in order to efficientlymanage multi-band Radio Frequencies (RFs) in a communication system thatsupports multi-band RFs and ID-related information is signaled totransmit and receive signals.

2. Discussion of the Related Art

The following description is given mainly focusing on a downlink (DL)mode in which a base station transmits signals to one or more terminals.However, it will be easily understood that the principle of the presentinvention described below can be directly applied to an uplink (UL) modesimply by reversing the procedure of the DL mode.

A technology in which one entity corresponding to a specific layer abovethe physical layer manages multiple carriers or frequency allocationbands (or simply frequency allocations (FAs)) has been suggested toefficiently use multiple bands or multiple carriers.

FIG. 1 schematically illustrates a method for transmitting and receivingsignals using multi-band RFs.

In (a) and (b) of FIG. 1, PHY0, PHY1, . . . PHY n−2, and PHY n−1represent multiple bends according to this technology and each of thebands may have a Frequency Allocation (FA) band size allocated for aspecific service according to a predetermined frequency policy. Forexample, the band PHY0 (RF carrier 0) may have a band size allocated fora general FM radio broadcast and the band PHY1 (RF carrier 1) may have aband size allocated for mobile phone communication. Although eachfrequency band may have a different band size depending on thecharacteristics of the frequency band, it is assumed in the followingdescription that each Frequency Allocation band (FA) has a size of A MHzfor ease of explanation. Each FA can be represented by a carrierfrequency that enables a baseband signal to be used in each frequencyband. Thus, in the following description, each frequency allocation bandwill be referred to as a “carrier frequency band” or will simply bereferred to as a “carrier” as it may represent the carrier frequencyband unless such use causes confusion. As in the recent 3GPP LTE-A, thecarrier is also referred to as a “component carrier” for discriminatingit from a subcarrier used in the multicarrier system.

From this aspect, the “multi-band” scheme can also be referred to as a“multicarrier” scheme or “carrier aggregation” scheme.

In order to transmit signals through multiple bands as shown in (a) ofFIG. 1 and to receive signals through multiple bands as shown in (b) ofFIG. 1, both the transmitter and the receiver need to include an RFmodule for transmitting and receiving signals through multiple bands. In(a) and (b) of FIG. 1, the method of configuring a “MAC” is determinedby the base station, regardless of the DL or UL mode.

Simply stated, the multi-band scheme is a technology in which a specificlayer entity (for example, one MAC entity), which will simply bereferred to as a “MAC” unless such use causes confusion, manages andoperates a plurality of RF carriers to transmit and receive signals. RFcarriers managed by one MAC do not need to be contiguous. Accordingly,this technology has an advantage of high flexibility in management ofresources.

For example, frequencies may be used in the following manner.

FIG. 2 illustrates an example wherein frequencies are allocated in amulti-band-based communication scheme.

In FIG. 2, bands FA0 to FA7 can be managed based on RF carriers RF0 toRF7. In the example of FIG. 2, it is assumed that the bands FA0, FA2,FA3, FA6, and FA7 have already been allocated to specific existingcommunication services. It is also assumed that RF1 (FA1), RF4 (FA4),and RF5 (FA5) can be efficiently managed by one MAC (MAC #5). Here,since the RF carriers managed by the MAC need not be contiguous asdescribed above, it is possible to more efficiently manage frequencyresources.

In the case of downlink, the concept of the multi-band-based schemedescribed above can be exemplified by the following basestation/terminal scenario.

FIG. 3 illustrates an example scenario in which one base stationcommunicates with a plurality of terminals (UEs or MSs) in amulti-band-based scheme.

In FIG. 3, it is assumed that terminals 0, 1, and 2 have beenmultiplexed. The base station 0 transmits signals through frequencybands managed by carriers RF0 and RF1. It is also assumed that theterminal 0 is capable of receiving only the carrier RF0, the terminal 1is capable of receiving both the carriers RF0 and RF1, and the terminal0 is capable of receiving all the carriers RF0, RF1, and RF2.

Here, the terminal 2 receives signals of only the carriers RF0 and RF1since the base station transmits only the carriers RF0 and RF1.

However, the above multi-band-based communication scheme has only beenconceptually defined and an ID specification method, which enables moreefficient management of each frequency allocation band, and a method forsignaling ID-related information have not been defined in detail.

SUMMARY OF THE INVENTION

An object of the present invention devised to solve the problem lies onproviding a method for transmitting and receiving signals, wherein IDinformation of multiple frequency bands is specified in amulti-band-based communication system and a method for efficientlysignaling ID-related information to achieve improved signal transmissionand reception.

Another object of the present invention devised to solve the problemlies on providing a method for transmitting ID information of multiplefrequency bands while overcoming the Peak-to-Average Ratio (PAPR)problem.

In accordance with an embodiment of the present invention, the above andother objects can be achieved by providing a method for transmittingsignals, the method including transmitting an information unit of aspecific layer above a physical layer through a plurality of frequencyallocation bands managed by an entity corresponding to the specificlayer, and transmitting control information identifying each of theplurality of frequency allocation bands, wherein each of the pluralityof frequency allocation bands managed by the entity has a band size forallocation for a specific service according to a predetermined frequencypolicy and the control information identifying each of the plurality offrequency allocation bands includes a second ID into which a first IDhas been converted, the first ID identifying each of the plurality offrequency allocation bands in the physical layer, the second IDidentifying each of the plurality of frequency allocation bands managedby the entity in the physical layer.

Here, the control information may include the first ID and the second IDfor each of the plurality of frequency allocation bands managed by theentity and may be transmitted through at least one of a preamble or acontrol signal.

When the control information is transmitted through the preamble, thecontrol information may be identified through a different preamble codeor a different preamble timing offset. Here, the preamble timing offsetmay be applied as a timing offset of the entirety of a frame includingthe preamble.

In addition, the control information of each of the plurality offrequency allocation bands managed by the entity may be individuallyspecified for each of the plurality of frequency allocation bands.Alternatively, the plurality of frequency allocation bands managed bythe entity may be divided into at least one primary carrier frequencyband and at least one subsidiary carrier frequency band, and the atleast one primary carrier frequency band may be set to include controlinformation of a predetermined number of subsidiary carrier frequencybands.

Here, the at least one primary carrier frequency band may include aplurality of primary carrier frequency bands. In this case, each of theplurality of primary carrier frequency bands may be used to transmitinformation of a predetermined number of subsidiary carrier frequencybands.

In accordance with another embodiment of the present invention, theabove and other objects can be achieved by providing a method forreceiving signals, the method including receiving an information unit ofa specific layer above a physical layer through a plurality of frequencyallocation bands managed by an entity corresponding to the specificlayer, and receiving control information identifying each of theplurality of frequency allocation bands, wherein each of the pluralityof frequency allocation bands managed by the entity has a band size forallocation for a specific service according to a predetermined frequencypolicy and the control information identifying each of the plurality offrequency allocation bands includes information of a second ID intowhich a first ID has been converted, the first ID identifying each ofthe plurality of frequency allocation bands in the physical layer, thesecond ID identifying each of the plurality of frequency allocationbands managed by the entity in the physical layer.

According to each of the embodiments of the present invention describedabove, it is possible to more efficiently manage a plurality of carrierfrequency bands managed by one entity and the receiving side can moreeasily set a procedure for receiving signals through a plurality ofcarriers.

In addition, according to the embodiment wherein a timing offset isapplied to the entirety of a frame or to a preamble (synchronouschannel) transmitted in the frame, it is possible to distribute the timeof signal transmission, thereby reducing the PAPR.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 schematically illustrates a method for transmitting and receivingsignals using multi-band RFs.

FIG. 2 illustrates an example wherein frequencies are allocated in amulti-band-based communication scheme.

FIG. 3 illustrates an example scenario in which one base stationcommunicates with a plurality of terminals (UEs or MSs) in amulti-band-based scheme.

FIG. 4 illustrates an example method for identifying a carrier ID usinga preamble timing offset according to this embodiment.

FIG. 5 illustrates another embodiment of the method for identifying acarrier ID using a preamble timing offset.

FIG. 6 illustrates another embodiment of the method for identifying acarrier ID using a preamble timing offset.

FIGS. 7 and 8 illustrate another embodiment of the method foridentifying a carrier ID using a preamble timing offset.

FIG. 9 illustrates the concept that all carrier-related controlinformation is transmitted using a primary carrier according to anembodiment of the present invention.

FIG. 10 illustrates the concept that one primary carrier is specifiedand the primary carrier controls remaining subsidiary carriers.

FIG. 11 illustrates the concept that two primary carriers are specifiedand each of the two primary carriers controls a predetermined number ofsubsidiary carriers.

FIG. 12 illustrates a method in which a plurality of primary carrierssupports each group including a plurality of terminals according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention with reference to the accompanying drawings. Thedetailed description, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present invention, rather than to show the only embodiments that canbe implemented according to the invention.

The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details. In some instances, knownstructures and devices are omitted or are shown in block diagram form,focusing on important features of the structures and devices, so as notto obscure the concept of the present invention. The same referencenumbers will be used throughout this specification to refer to the sameor like parts.

The present invention suggests an ID specification method, which allowsone MAC to efficiently manage a plurality of RF carriers, and a methodfor signaling ID-related information. In the following description, theterm “Media Access Control (MAC) layer” is used as a general termdescribing a layer (for example, a network layer) above the Physical(PHY) layer (Layer 1) among the 7 OSI layers, which is not necessarilylimited to the MAC layer. Although the following description has beengiven with reference to an example where multi-band RFs are contiguous,the multiple bands according to the present invention do not necessarilyinclude physically contiguous RF carriers as described above withreference to FIG. 2. In addition, although the bandwidth of each RFcarrier is described below as being equal for ease of explanation, thepresent invention may also be applied to the case where the bandwidthsof frequency bands managed based on each RF carrier are different. Forexample, an RF frequency band (RF0) of 5 MHz and an RF frequency band(RF1) of 10 MHz may be managed by one MAC entity.

In addition, although RF carriers in the present invention may be thoseof the same system, the RF carriers may also be those to which differentRadio Access Technologies (RATs) are applied. For example, we canconsider an example wherein the 3GPP LTE technology is applied to RF0and RF1, the IEEE 802.16m technology is applied to RF2, and the GSMtechnology is applied to RF3.

An embodiment of the present invention suggests that the position ofeach frequency band in an actual physical layer managed by one MAC bemanaged by conversion into a logical index. In addition, it is assumedthat the maximum number of RF carriers managed by one MAC in one systemis limited to M.

The following is a detailed description with reference to the example ofFIG. 2 wherein the MAC #5 manages RF carriers.

In the example of FIG. 2, it is assumed that the maximum number of RFcarriers managed by one MAC is 3. It is also assumed that the 3 RFcarriers are named RF1, RF4, and RF5 which are absolute frequency bandindex values. In this case, the physical frequency indices RF1, RF4, andRF5 can be managed by conversion into logical indices 0, 1, and 2according to this embodiment.

Accordingly, there is a need to provide a method for signalingcarrier-ID-related information to the receiving side according to thisembodiment. Signaling of the maximum number of carriers managed by oneMAC may be needed in some cases.

When the maximum number of carriers managed by one MAC is M, thisembodiment suggests two ID signaling methods: 1) a method in which IDinformation is transmitted through a preamble and 2) a method in whichID information is transmitted through a common control signal, abroadcast channel, or the like. Possible methods for signaling IDinformation using a preamble include a method in which a differentsignature is included in a preamble to be transmitted and a method inwhich an offset is applied to the timing of transmission of a preamble.Applying an offset to the preamble transmission timing may be construedas applying the offset not only to the timing of transmission of thepreamble but also to the timing of transmission of the entirety of aframe including the preamble.

Although it is assumed in the above example that one carrier includesone carrier ID, it is also possible to define one logical carrier IDinto which one or more physical carrier IDs are grouped. Here, thepreamble is a signal that is transmitted through a synchronous channel.Accordingly, the preamble will be used as a concept identical to orincluding the synchronous channel.

First, reference will be made to a method for selectively signalinginformation regarding the number of carriers managed by one MAC togetherwith each carrier ID as described above through a preamble.

As an example of the carrier ID signaling method described above, anembodiment of the present invention suggests a method in which adifferent signature is allocated to each carrier ID. As a specificmethod for providing a different signature for each carrier ID, thisembodiment suggests a method in which a different code is allocated toeach carrier ID and a method in which each carrier ID is indicated by apreamble transmission timing offset or a frame transmission timingoffset.

Although this embodiment has been described such that one preamble istransmitted per carrier for case of explanation, a plurality ofpreambles may also be transmitted per carrier.

It is possible to apply the same concept as described above ifsynchronous channel configurations such as a P-SCH and an S-SCH whichwill be used in the 3GPP LTE evolution are grouped and the group isregarded as a preamble in this embodiment.

Reference will now be made to a method for allocating a different codeto each carrier ID as a more specific embodiment of the presentinvention.

First, this embodiment suggests a method for indicating a differentcarrier ID through a different code. Generally, a preamble is used todetect a cell ID. For example, when there is a need to identify a totalof 114 cell IDs, it is required that they be identified using at least114 different codes and, when there is a need to identify 4 additionalcarrier IDs according to this embodiment, it is required that a total of456 (=114*4) different codes be allocated. Here, the term “differentcodes” refers to codes that can be discriminated from each other and maybe a set of codes which are correlated with each other at apredetermined correlation level or less, a set of circular shiftsequences, a set of sequences covered by orthogonal sequences, or thelike and need not be limited to any specific code types.

In addition, another embodiment of the present invention using the aboveconcept suggests that carriers representing respective frequencyallocation bands be discriminated and used according to the usages ofthe carriers.

Specifically, this embodiment suggests that at least one of a pluralityof carriers be defined as a primary carrier. This primary carrier is acarrier, for which the terminal initially attempts to search wheninitial cell search or initial neighbor cell search is performed.Generally, the primary carrier can be used to transmit a systemconfiguration indicating a multi-carrier configuration or a systembandwidth, a common control signal, or broadcast information. In thiscase, the terminal only needs to determine whether the correspondingcarrier is a primary carrier or a different carrier which is referred toas a “subsidiary carrier” in the following description.

In this case, it is preferable that two codes be additionally allocatedin order to identify the usage of each carrier. Here, it is to be notedthat the purpose of the two additionally allocated codes is not toidentify carrier IDs in the above example. In this example, when thenumber of carrier IDs is 114, the total number of needed codes is 228(=114*2).

Reference will now be made to a method for identifying a carrier IDusing a preamble timing offset as another embodiment of the presentinvention.

FIG. 4 illustrates an example method for identifying a carrier ID usinga preamble timing offset according to this embodiment.

In this example, a primary carrier and a subsidiary carrier arediscriminated (i.e., identified) using two types of preamble signatures.More specifically, a signature 0 is used for the primary carrier and asignature 1 is used for the subsidiary carrier in the example of FIG. 4.

In this example, a timing offset value of one carrier unit is set to “d”as shown in FIG. 4. The “d” value may be set to various values asdescribed below.

First, in an embodiment of the present invention, the “d” value can beset to be less than a preamble transmission period or a synchronouschannel transmission period. For example, in the case of the 3GPP LTEsystem, P-SCH and S-SCH signals included in a synchronous channel aretransmitted every 5 ms which is the length of a subframe (where theP-SCH signal will hereinafter be referred to as a “PrimarySynchronization Signal (PSS)” and the S-SCH signal will hereinafter bereferred to as a “Secondary Synchronization Signal (SSS)”) and two pairsof PSSs and SSSs are transmitted in a 10 ms frame including twosubframes.

Two SSSs transmitted in 10 ms have different signatures (for example,two short swapped sequences) so that the receiving side can determinewhether a corresponding subframe in a 10 ms frame is a subframe 0 or asubframe 1. Under this assumption, the “d” value can be set to 5 ms.

In another embodiment of the present invention, the “d” value can be setto be equal to or greater than the preamble transmission period or thesynchronous channel transmission period. For example, in the case of the3GPP LTE system, it may be difficult to derive, from only thesynchronous channel, the “d” value set to be equal to or greater thanthe synchronous channel transmission period since the same SSS isrepeated every 10 ms in the 3GPP LTE system. In this case, thisembodiment suggests that the “d” value be derived through a System FrameNumber (SFN).

In the 3GPP LTE system, the SFN is transmitted through a P-BCH includedin a subframe 0 (0-4905). When it is assumed that the “d” value has beenset to 10 ms, the SFN of the carrier 0 is 10 and the SFN of the carrier1 is 11 and therefore it is possible to derive the “d” value. The SFN isincremented by one every 10 ms.

A different “d” value may be set for each RF carrier. Here, the “d”value may have a circular shift form on an OFDM symbol basis or may be adelay value on a smaller unit basis.

When the delay value is controlled in a circular shift form, this can bedirectly applied to the time domain or can be applied to the frequencydomain. A circular shift may be set to be equally applied to everysignal (for example, a Reference Signal (RS) and data) transmittedthrough each carrier band or a circular shift may be set to be appliedto only the reference signal or the preamble. That is, whiletransmission data is left unchanged, only the reference signal or thepreamble can be transmitted so as to have an offset according to the “d”value. In another method, while transmission data is left unchanged,only the SFN transmitted in the P-BCH can be incremented. This canreplace the above method in which the preamble/synchronous channel orreference signal is transmitted with an offset applied thereto accordingto the “d” value. A method in which transmission data elements are alsotransmitted with an offset applied thereto and the SFN is set to beincremented accordingly may also be applied.

For reference, the SFN in the 3GPP LTE system consists of 12 bits. Themore significant 10 bits among 12 bits are explicitly transmittedthrough a P-BCH corresponding to 40 ms and may have a value of 0-1023during 40 ms. The less significant 2 bits among the 12 SFN bits can bederived through blind decoding based on a unique start position (RV) ofa circular buffer.

When a timing offset is applied to a signal transmitted through eachcarrier band as in the above embodiment, it is possible to achieve anadvantage of reduction in the PAPR of the transmission signal. Here, letus assume that four carriers are transmitted using one RF module in the3GPP LTE system. In this case, a problem may occur in the PAPR sincefour carriers are all transmitted based on the same physical cell ID.However, it is possible to achieve an advantage of reduction in the PAPRby setting a different transmission timing for each carrier band asdescribed above. Accordingly, according to the above embodiment, themethod in which a different timing offset is applied to each carrier canalso be used to reduce the PAPR. Here, to apply a different timingoffset to each carrier, the circular shift may be applied both in thetime domain and in the frequency domain as described above.

In addition, in another embodiment of the present invention, it ispossible to set the “d” value in various manners so that the receivingside can determine the “d” value through combination of thepreamble/synchronous channel and the SFN described above.

For example, although the “d” value is set on the basis of a P-BCH (10ms) to apply an offset in the above description, it is also possible toset the “d” value on the basis of four P-BCHs (i.e., on a 40 ms basis)to apply an offset.

The embodiment as shown in FIG. 4 has an advantage in that acorresponding carrier ID can be efficiently detected through a smallamount of calculation. The embodiment as shown in FIG. 4 also has anadvantage in that there is no need to perform additional controlsignaling for carrying the carrier ID. For example, the terminal (MobileStation (MS) or User Equipment (UE)) may perform initial processes forsignal processing in the following order.

-   -   1. The terminal searches for a primary carrier through a        preamble signature “0” (i.e., carrier ID=0) and achieves time        synchronization.    -   2. The terminal achieves time synchronization through a preamble        of a signature “1” for a specific carrier.    -   3. The terminal detects a current carrier ID using a time offset        from the primary carrier.

FIG. 5 illustrates another embodiment of the method for identifying acarrier ID using a preamble timing offset.

In the example of FIG. 5, all carriers use the same preamble signature(code) and the carrier ID is represented by a timing offset. Here, it ispreferable that an indicator representing the carrier ID be transmittedat a position adjacent to the preamble of the primary carrier in orderto provide a reference for timing offset comparison. In FIG. 5, thisindicator is shown by “Primary carrier ID indicator”.

According to this embodiment, for example, the terminal may performinitial processes for signal processing in the following order.

-   -   1. The terminal searches for a primary carrier through a        preamble signature “0” and a primary carrier indicator (i.e.,        carrier ID=0) and achieves time synchronization.    -   2. The terminal achieves time synchronization through a preamble        of a signature “0” for a specific carrier.    -   3. The terminal detects a current carrier ID using a time offset        from the primary carrier.

The following is a description of another example of transmission ofcarrier ID information for each carrier, similar to the embodiment ofFIG. 5.

FIG. 6 illustrates another embodiment of the method for identifying acarrier ID using a preamble timing offset.

In the method of the embodiment shown in FIG. 6, a control signalindicating the carrier ID is transmitted in each carrier. In this case,once a carrier ID is detected, the terminal can detect all remainingcarrier IDs at the preamble detection step without decodingcorresponding control signal information.

FIGS. 7 and 8 illustrate another embodiment of the method foridentifying a carrier ID using a preamble timing offset.

Specifically, although the method of FIG. 7 is similar to that of FIG.6, an ID indicator for the primary carrier and an ID indicator for thesubsidiary carrier are separately transmitted in the method of FIG. 7.Although the method of FIG. 8 is similar to that of FIG. 6, a differentpreamble code is used for each carrier ID and different carrierindication information is also defined for each carrier ID in the methodof FIG. 8.

While the main feature of the above embodiments of the present inventionis that information regarding a carrier ID is transmitted using a timingoffset, carrier information may be transmitted using various othermethods. Applying an offset to the preamble transmission timing in theembodiments described above with reference to FIGS. 4 to 8 can beconsidered identical to applying a time offset to the entirety of aframe including the corresponding preamble to transmit informationregarding the carrier ID.

An embodiment wherein carrier-related information according to thepresent invention is transmitted through a common control channel(broadcast channel) can also be provided. A carrier ID defined accordingto the present invention can be transmitted through a broadcast channelor a control signal for each carrier. For example, in the case of theIEEE 802.16m supporting the legacy mode, a carrier ID can be signaledusing a reserved bit among 5 DLFP bits of a broadcast channel used inthe conventional IEEE 802.16e and can also be signaled through a DL-MAP.Alternatively, a new DLFP/DL-MAP format may be defined to transmit thecarrier ID. In the case of 3GPP LTE, a carrier ID can be transmittedthrough a broadcast channel (BCH).

More specifically, in the case of 3GPP LTE, information indicatingwhether the corresponding carrier is a primary carrier or a subsidiarycarrier can be transmitted using 1-bit signaling through a PhysicalBroadcast Channel (P-BCH). That is, the primary carrier may be signaledthrough a bit value “0” and the subsidiary carrier may be signaledthrough a bit value “1” in the P-BCH. Alternatively, the primary carriermay be signaled through a bit value “1” and the subsidiary carrier maybe signaled through a bit value “0” in the P-BCH. Here, the primarycarrier is a carrier that the terminal initially attempts to access asdescribed above.

Reference will now be made to a method for transmitting a control signal(a carrier-related control signal such as a carrier ID) through aprimary carrier as another embodiment of the present invention.

This embodiment suggests that all carrier IDs or control signals managedby a MAC be transmitted using a primary carrier defined according to anembodiment of the present invention. When all carrier-ID-relatedinformation is transmitted using the primary carrier, carrier indicesthat can be managed by one MAC, logical indices of available frequencybands, or physical indices occupied by the subsidiary carrier can be setto be transmitted using the primary carrier. In the description of thepresent invention, the MAC is only an example of a specific layer whichis located above the physical layer and which can manage a plurality ofcarriers as described above. The “MAC” includes not only the conceptdefined in IEEE but also the concept of a MAC present for each carrierband in the 3GPP system.

The following is a description of the example illustrated in FIG. 2.Here, let us assume that the bands FA1, FA4, and FA5 are frequencyallocation bands available in the multi-carrier-based system while theband FA1 is a primary carrier frequency band. In this case,multi-carrier-related control information can be transmitted through theprimary carrier frequency band FA1 according to this embodiment. Sincethe bands FA0 to FA7 can be used in the system in this embodiment,carrier indices 1, 4, and 5 covered by the corresponding MAC can betransmitted as a control signal of the primary carrier. In analternative method, when the indices 1, 4, and 5 of the physicalchannels FA1, FA4, and FA5 are converted to logical indices, it ispossible to signal a logical index 0 located at the physical channelFA1, a logical index 1 located at the physical channel FA4, and alogical index 2 located at the physical channel FA5 in the primarycarrier. It is also possible to transmit all the control signalsdescribed above.

FIG. 9 illustrates the concept that all carrier-related controlinformation is transmitted using a primary carrier according to anembodiment of the present invention.

Here, the control signals transmitted in the primary carrier include alltypes of control signals described above such as a carrier-relatedcontrol signal, a general control signal, and a carrier ID asconceptually illustrated in FIG. 9.

In the above embodiments, the preamble of each carrier in the case wherea control signal is transmitted using the primary carrier may or may notbe identical. The method in which all carrier-related information istransmitted using the primary carrier according to the embodiments canbe used in combination with the embodiment wherein carrier informationis transmitted using the preamble.

In the above description, carriers managed by one MAC include only oneprimary carrier. However, carriers managed by one MAC may include aplurality of primary carriers and the following description will begiven focusing on the case where two or more primary carriers areincluded in carriers managed by one MAC.

A method in which carrier-related information is separately defined andtransmitted using a preamble, a timing offset, or the like and a methodin which all carrier-related information is transmitted using a primarycarrier can both be applied according to the present invention. However,the following description will be given focusing on the case where allcarrier-related information is transmitted using a primary carrier forease of explanation.

FIG. 10 illustrates the concept that one primary carrier is specifiedand the primary carrier controls remaining subsidiary carriers.

FIG. 11 illustrates the concept that two primary carriers are specifiedand each of the two primary carriers controls a predetermined number ofsubsidiary carriers.

In the method illustrated in FIG. 10, one primary carrier signals andmanages all carrier-related information of the n−1 remaining carriers.On the other hand, in the method illustrated in FIG. 11 according tothis embodiment, two primary carriers transmit carrier-relatedinformation of two groups of subsidiary carriers, into which allremaining subsidiary carriers are divided, respectively.

When a plurality of primary carriers is specified according to thisembodiment as shown in FIG. 11, there is an advantage in that it ispossible to support more flexible configurations when a number ofterminals are multiplexed. For example, let us assume that one MACmanages 6 carriers, the number of terminals belonging to the MAC is 6,and the 6 terminals are divided into two groups, each including 3terminals. In this case, it is possible to support terminalscorresponding to each group in the following manner.

FIG. 12 illustrates a method in which a plurality of primary carrierssupports each group including a plurality of terminals according to anembodiment of the present invention.

In this method, an RF carrier 0 and an RF carrier 3, which are primarycarriers, can manage information regarding remaining carriers and 2groups of terminals (MSs) into which 6 terminals are divided can beallocated respectively to 2 carrier groups managed by the respectiveprimary carriers to provide services.

Although 6 terminals are divided into 2 groups to perform communicationin the example of FIG. 12, the terminals may be divided into n groups(other than 2 groups) according to the number of primary carriers toreceive services.

The detailed description of the preferred embodiments of the presentinvention has been given to enable those skilled in the art to implementand practice the invention. Although the invention has been describedwith reference to the preferred embodiments, those skilled in the artwill appreciate that various modifications and variations can be made inthe present invention without departing from the spirit or scope of theinvention described in the appended claims. Accordingly, the inventionshould not be limited to the specific embodiments described herein, butshould be accorded the broadest scope consistent with the principles andnovel features disclosed herein.

The signal transmission/reception method according to each of the aboveembodiments of the present invention can be widely used for amulti-carrier system in which one MAC entity manages a plurality ofcarrier frequency bands as described above. That is, the signaltransmission/reception method according to each of the above embodimentsof the present invention can be applied to any system, regardless ofwhether it is a 3GPP LTE system or an IEEE 802.16m system, provided thatthe system is applied as a multi-carrier system as described above.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for transmitting, by a base station,signals in a communication system, the method comprising: transmitting,to a mobile station via a primary carrier band, control information fora subsidiary carrier band; and transmitting data to the mobile stationvia the subsidiary carrier band based on the control information and viathe primary carrier band, wherein the primary carrier band is a carrierfrequency band which the mobile station initially attempts to access orvia which information of a carrier aggregation configuration istransmitted, wherein the control information includes a logical indexassigned to the subsidiary carrier band for the mobile station and aphysical index of a frequency allocation band used as the subsidiarycarrier band, wherein the physical index corresponds to one of pluralabsolute frequency band indexes assigned to frequency allocation bandsavailable in the communication system, wherein the logical indexassigned to the subsidiary carrier band identifies the subsidiarycarrier band from among a plurality of frequency allocation bandsmanaged by a medium access control (MAC) layer, and wherein the primarycarrier band has a logical index of ‘0’ and the logical index assignedto the subsidiary carrier band is other than ‘0’.
 2. The method of claim1, wherein the logical index assigned to the subsidiary carrier band isan integer value between ‘1’ and a maximum number of frequencyallocation bands managed by a specific layer above a physical layer—1.3. The method of claim 2, wherein the specific layer is the MAC layer.4. The method of claim 1, wherein the base station uses only one primarycarrier band for the mobile station.
 5. The method of claim 1, whereinthe transmitting the data to the mobile station via the subsidiarycarrier band and the primary carrier band comprises carrier aggregation.6. The method of claim 1, wherein the control information comprises thecarrier aggregation configuration.
 7. A method for receiving, by amobile station, signals from a base station in a communication system,the method comprising: receiving, by the mobile station via a primarycarrier band, control information for a subsidiary carrier band; andreceiving, by the mobile station, data via the subsidiary carrier bandbased on the control information and via the primary carrier band,wherein the primary carrier band is a carrier frequency band which themobile station initially attempts to access or via which information ofa carrier aggregation configuration is transmitted, wherein the controlinformation includes a logical index assigned to the subsidiary carrierband for the mobile station and a physical index of a frequencyallocation band used as the subsidiary carrier band, wherein thephysical index corresponds to one of plural absolute frequency bandindexes assigned to frequency allocation bands available in thecommunication system, wherein the logical index assigned to thesubsidiary carrier band identifies the subsidiary carrier band fromamong a plurality of frequency allocation bands managed by a mediumaccess control (MAC) layer, and wherein the primary carrier band has alogical index of ‘0’ and the logical index assigned to the subsidiarycarrier band is other than ‘0’.
 8. The method of claim 7, wherein thelogical index assigned to the subsidiary carrier band is an integervalue between ‘1’ and a maximum number of frequency allocation bandsmanaged by a specific layer above a physical layer—1.
 9. The method ofclaim 8, wherein the primary and subsidiary carrier bands are managed bythe MAC layer of the base station.
 10. The method of claim 7, whereinthe mobile station uses only one primary carrier band for the basestation.
 11. The method of claim 7, wherein the receiving, by the mobilestation, the data via the subsidiary carrier band and the primarycarrier band comprises carrier aggregation.
 12. The method of claim 7,wherein the control information comprises the carrier aggregationconfiguration.